[Podman] proper way to detect running inside a container?

dropped into existing project, where all Makefiles do the following test to see if they're running inside docker: ifneq ($(wildcard /.dockerenv),) i'm pretty sure that's just asking for trouble, and i've perused a github issue related to that: https://github.com/containers/libpod/issues/648 so what is the *proper* way to detect if one is running inside a container? the way that seems most reliable is to check /proc/1/sched. thoughts? rday